This type of study was a systematic review of other studies, in which the results were collated. Also worth noting (unlike last week): none of the authors work for tobacco companies. (To learn the difference between different types of scientific study, click here).

Purpose of the study

This interested me somewhat. They basically said "OK, so there might be toxic metals in e-cig vapour. BUT - are they at dangerous levels?"

So they didn't argue on whether there was or wasn't toxic metal in e-cig vapour. Instead they assessed, if toxic metals were detected, were they at levels likely to cause any real harm?

Methods

The authors conducted a literature search and found nine studies analysing the toxic metal components of e-cig vapour. They discounted the ones assessing environmental impacts as the levels of metals were much lower, leaving them with two studies that examined the levels in the vapour itself.

Let's call the two studies Goniewicz et al. and Williams et al. (mainly because that's what the authors of this study called them).

Goniewicz et al.

This crew took twelve e-cigs and measured their metal by-products with a mass spectrometer. They compared their results to pharmaceutical nicotine inhalers.

They specifically measured for arsenic, barium, cadmium, chromium, cobalt, copper, lead, manganese, nickel, rubidium, strontium and zinc. Of all these metals, they only found evidence of cadmium, lead and nickel.

They also took blank sample measurements, i.e. they measured the air in the room in the mass spectrometer as a control. They then subtracted the levels detected in the blank samples from the e-cig samples to give a true indication of what was present in the e-cig vapour.

Williams et al.

This mob took the grand total of one e-cig and measured the vapour products (it is not stated how they did this).

They said they took room samples, but didn't report on the levels they found and didn't subtract the values from their one e-cig sample.

So, in short, it was a pretty average study.

Measurements

Farsalinos, Voudris & Poulas measured the levels found against two metrics - the United States Pharmacopia (USP) Permissible Daily Exposure (PDE) levels, and for the metals that weren't referenced in the USP list, they used the Minimal Risk Level (MRL) as dictated by the Agency for Toxic Substances and Disease Registry (ATSDR). They also used the stricter of the two measures where there was any doubt.

The thinking behind this was to measure the worst-case scenario of toxic metal existence against levels generally recognised as safe for medicinal inhalers and other nicotine replacement therapies.

Next they had to estimate how many puffs per day the average vaper takes, and what the levels of these metals would be extrapolated to the average daily exposure in order to properly measure against the USP PDE and the ATSDR MRL. Based on a previous study (Farsalinos et al. 2013) which determined an average consumption of 5mg of vapour per puff, and based on another previous study (Farsalinos et al. 2014) which determined the average daily consumption to be 3g, they assumed a level of 600 puffs per day to be the average. Then (just to be safe) they gave it an uncertainty factor of 2 and worked off a baseline of 1200 puffs per day.

Multiplying the results according to numbers of puffs, then averaging it across the amount of air typically inhaled in a daily period, carry the two and divide by the number you first thought of, and you'll have the daily exposure levels you get from these metals from e-cigs.

Results

Although the Williams et al. study was a bit average, the authors included the results anyway. Below are the metals and their amounts compared to the daily safe limits across the various measures:

Metal

Avg. Detected in:

Min. safe amt.

% of daily safe limit

Goniewicz et al. study

Williams et al. study

Aluminium

NM

47.28

22500.00

0.210%

Barium

0

1.44

2250.00

0.064%

Cadmium

0.57

NM

1.50

38.000%

Chromium

0

0.84

25.00

3.360%

Copper

0

24.36

70.00

34.800%

Iron

NM

62.4

22500.00

0.277%

Lead

0.59

2.04

5.00

40.800%

Manganese

0

0.24

3.24

7.407%

Nickel

0.29

0.6

1.50

40.000%

Tin

NM

4.44

9000.00

0.049%

Titanium

NM

0.24

1350.00

0.018%

Zinc

0

6.96

22500.00

0.031%

Zirconium

NM

0.84

22500.00

0.004%

So... if I'm reading this correctly, even using the strictest measures, and even using terrible data, and even at twice the average vape rate, the levels of toxic metals are still way below the maximum safe daily threshold, even based on the standards for inhaled medicines... in fact, you'd probably get the same kind of dose just walking down Rundle Mall.

Conclusion

The authors of the study say it best:

"In conclusion, the levels of metals emitted to the [e-cigarette] aerosol, as found in currently available literature, are unlikely to generate significant adverse health effects for smokers switching to [e-cigarette] use" (Farsalinos, Voudris & Poulas, 2015, pg. 5228).

What this means for you

If you were worried about the possibility of inhaling toxic metals when you vape, you probably don't have to - even if you are, they are nowhere near the kind of levels needed to do you any damage.

The main message is still what it has always been - vaping is about harm reduction. We vape because we want a safer alternative to smoking tobacco - both for us and the people close to us.

No responsible vaper I have ever met is in favour of the idea of giving e-cigs to kids, or getting non-smokers hooked. We just want to be able to vape ourselves, save money and save our health.

Farsalinos, K., Voudris, V., & Poulas, K. (2015). Are Metals Emitted from Electronic Cigarettes a Reason for Health Concern? A Risk-Assessment Analysis of Currently Available Literature. International Journal Of Environmental Research And Public Health, 12(5), 5215-5232. doi:10.3390/ijerph120505215

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